The research carried out under this grant revolves aroung the "Penthouse", a human nutrition metabolic unit. This is a six-bed facility which enables the human nutrition research group to carry out long-term, carefully controlled studies of nutritional variables. Most of the studies utilize normal volunteers, but studies have been performed with subjects suffering from abnormalities. Our research activities tend to focus on several integrated areas which we consider of great importance. These are as follows: (1) protein and energy utilization requirements of young and mature adults; (2) nutrition and its relationship to reproduction; (3) the effects of nutrients on the ecology of the gut; (4) mineral metabolism, especially of calcium and trace minerals; (5) availability of nutrients, especially from food; (6) studies in obesity. It has also been our practice, when feasible, to carry out certain types of out-patient studies. BIBLIOGRAPHIC REFERENCES: Margen, Sheldon and Janet C. King. The effect of oral contraceptive agents on the metabolism of some trace elements. Am. J. Clin. Nutr. 28:392, 1975. Crim, Marilyn C., D.H. Calloway and Sheldon Margen. Creatine metabolism in men: Creatine pool size and turnover in relation to creatine intake. J. Nutr. 106:371, 1976.